T.A.
I'm with Tuesday on this one. He is being a great big fat baby.
BUT I think it is important that you do what you can and he should know that. However, if you ever use that as a reason not to do something with him, he'll feel it right away and he'll resent you for it. Perhaps he's starting to think that.
Maybe you should sit down with him and calmly explain that while you will do what you can, he needs to lay off when you're not feeling well. It is selfish and immature for him to treat you this way when he doesn't get what he wants. His manipulation is unfair and childish and that attitude doesn't exactly put you in the mood.